This invention relates to a needlestick prevention device for use with injection devices, such as syringes.
A needlestick injury generally occurs in a medical environment, and particularly before or after use of a syringe or other injection device, when the user accidentally sticks the needle into himself or herself, or indeed another person. It is of course important to prevent such injuries, since they can spread infections and diseases, as well as being painful and possibly incapacitating.
There are several known ways of trying to prevent needlestick injuries. For example, some syringes are made with needles which are retracted automatically after use by means of a spring in the syringe. However, this requires a complex construction, and is expensive to manufacture. Further, it does not address the possibility of injury occurring before the injection is given.
Another known way is to replace the tubular sheath which is supplied with the syringe, protecting the needle. It is not now recommended practice to replace the sheath after the syringe has been used, because of the difficulty of placing the end of the needle accurately in the sheath. It is thought that trying to re-sheath the needle has actually been the cause of a significant number of needlestick injuries. Further, the sheath can easily be removed again, so that injury is possible.
Yet another known needlestick prevention device is an automatic needle sheath mounted on the syringe barrel, the sheath being able to slide out to cover the needle. EP-A-0 268 445 shows a construction with a stationary sheath part, and a movable sheath part spring-biassed to an extended position in which it covers the needle. The movable sheath part retracts to expose the needle for use, and when the retracting pressure is released the spring moves it automatically into its extended position, where it is locked. The movable sheath part has a projection received in a track in the stationary part to determine its movement and to lock it. Again, this is a relatively complex construction which is expensive to manufacture. A similar construction is found in WO 03/105935.